This invention relates to a level.
The conventional carpenter""s level, which is used for testing whether a nominally horizontal (or vertical) surface is in fact horizontal (or vertical), within an acceptable tolerance, comprises a frame, typically made of a metal such as aluminum alloy, having at least one flat guide surface and two bubble vials mounted in the frame. The level is positioned with the guide surface against the surface to be tested. One vial is oriented relative to the guide surface for testing a nominally vertical surface and the other is oriented for testing a nominally horizontal surface. The typical level is about 2 feet long, although longer levels, e.g. four feet or six feet long, are also available.
The fact that conventional levels are available only in increments of about 2 feet in length gives rise to difficulty or inconvenience in using the conventional level. Imagine, for example, that you are installing a shelf inside a closet having a back wall about 3xe2x80x26xe2x80x3 wide between two side walls. You wish to attach a support to the back wall for supporting the rear edge of the shelf The support should be horizontal, and you wish to mark the position of the support at two locations, adjacent the side walls respectively. Obviously, since the back wall is only 3xe2x80x26xe2x80x3 wide, you cannot use a four foot level because there is not sufficient space between the two side walls. If you attempt to use a 2 foot level, you must place the markings in two steps, which is inconvenient and can cause errors.
In accordance with the invention there is provided a level comprising a frame defining first and second parallel channels, and first and second rails fitted slidingly in the first and second channels respectively, whereby the level is adjustable in length by sliding the rails in the respective channels.